PGT-A Embryo Testing — Should You Test Your Embryos Before Transfer?

One of the most significant advances in IVF over the past two decades is the ability to test embryos for chromosomal abnormalities before transfer — a technology known as Preimplantation Genetic Testing for Aneuploidy, or PGT-A. By identifying embryos with the correct number of chromosomes (euploid embryos) before transfer, PGT-A aims to improve the chances of a successful pregnancy and reduce miscarriage risk.

But should every IVF patient test their embryos? The answer is more nuanced than many clinics communicate. At Mother Hospitals & IVF Center in Hyderabad, Dr. E. Prashanthi Reddy takes an evidence-based approach to PGT-A — recommending it where it will genuinely improve outcomes, and being honest about its limitations for lower-risk patients. This guide explains what PGT-A is, how it works, who benefits most, and what it costs in India.

What Is Aneuploidy and Why Does It Matter?

Human cells normally contain 46 chromosomes arranged in 23 pairs. An aneuploid cell has too many or too few chromosomes — an extra chromosome (trisomy, as in Down syndrome) or a missing chromosome (monosomy). Chromosomal aneuploidy in embryos is the leading cause of:

• IVF failure — aneuploid embryos typically fail to implant or implant briefly then miscarry
• Early miscarriage — the most common cause of first-trimester pregnancy loss is chromosomal abnormality in the embryo
• Recurrent miscarriage — multiple consecutive pregnancy losses often reflect a pattern of aneuploid conception

Critically, aneuploidy rates in embryos increase dramatically with maternal age. At age 35, approximately 30–40% of embryos are aneuploid. By age 40, this rises to 60–70%, and by 42–43, 80% or more of embryos may be chromosomally abnormal. This is the primary biological reason why IVF success rates decline with age.

How PGT-A Works — Step by Step

Step 1: Embryo Culture to Blastocyst Stage

IVF embryos are cultured in the laboratory for 5–6 days until they reach the blastocyst stage. At this point, the embryo has approximately 100–200 cells and has differentiated into two distinct cell types: the inner cell mass (which will become the baby) and the trophectoderm (which will become the placenta).

Step 2: Trophectoderm Biopsy

The embryologist uses a specialised laser and microtool to remove a small cluster of 5–10 trophectoderm cells from the outer layer of the blastocyst. These placental precursor cells are biopsied rather than inner cell mass cells, minimising any effect on the developing embryo itself. The embryo is then vitrified (frozen) while the biopsy is sent for analysis.

Step 3: Genetic Analysis

The biopsied cells are sent to a specialist genetics laboratory. The most commonly used technology for PGT-A is next-generation sequencing (NGS), which provides a comprehensive chromosomal profile of all 24 chromosome types (22 autosomes plus X and Y). The laboratory typically returns results within 7–14 days.

Step 4: Embryo Classification

Embryos are classified as:

• Euploid: Normal chromosome number — recommended for transfer
• Aneuploid: Abnormal chromosome number — not transferred (unless in specific research contexts)
• Mosaic: A mixture of normal and abnormal cells — decision about transfer is complex and individualised
• No result: A small percentage of biopsies fail to yield a usable result; the embryo can be re-biopsied in some cases

Step 5: Frozen Embryo Transfer of Euploid Embryo

Once a euploid embryo is identified, it is transferred in a frozen embryo transfer cycle. Because PGT-A requires freezing and thawing, all PGT-A cycles are by definition freeze-all cycles.

Who Benefits Most From PGT-A?

The evidence for PGT-A is most compelling in specific patient populations:

Women Aged 37 and Over

The age-related increase in aneuploidy rates makes PGT-A most valuable for older patients. By identifying euploid embryos, PGT-A allows the transfer of the one embryo most likely to succeed from an otherwise age-burdened cohort. Per-transfer success rates improve significantly with PGT-A in this group. The critical question is whether cumulative live birth rates also improve — and for women 38+, the evidence increasingly suggests they do, by avoiding failed transfers and reducing miscarriage.

Couples with Recurrent Miscarriage (2 or More Losses)

When recurrent miscarriage is due to repeated conception of aneuploid embryos, PGT-A can break the cycle. It allows the identification of a chromosomally normal embryo before transfer, reducing the risk of another chromosomally driven loss. For this group, the emotional benefit of knowing the transferred embryo is euploid is also significant.

Patients with Repeated IVF Failure

If good-quality embryos have been transferred multiple times without a clinical pregnancy, high aneuploidy rates in the embryo cohort may be a contributing factor. PGT-A can identify whether this is the case and direct transfer resources toward euploid embryos only.

Carriers of Known Chromosomal Structural Abnormalities

Individuals who carry balanced chromosomal rearrangements (translocations or inversions) have a higher risk of producing aneuploid embryos. For these patients, preimplantation testing — often combining PGT-A with PGT-SR — is strongly recommended.

When PGT-A May Not Be Necessary

A major controversy in reproductive medicine is whether PGT-A benefits younger, good-prognosis IVF patients. Large randomised controlled trials, including the well-regarded STAR trial, found that in women under 35 with a good prognosis, PGT-A did not improve cumulative live birth rates compared to transferring untested embryos sequentially.

The reasons include:

• Young women produce fewer aneuploid embryos — PGT-A has less to "filter out"
• Some embryos classified as aneuploid are mosaic and may still be viable
• The biopsy process itself, while generally safe, carries a small risk of embryo damage
• Discarding mosaic embryos may reduce an otherwise adequate embryo cohort unnecessarily

For a 28-year-old with three good blastocysts and no history of miscarriage, transferring without PGT-A may be entirely appropriate. For a 41-year-old with two blastocysts and a previous miscarriage, PGT-A is a well-justified investment.

The Mosaic Embryo Question

Mosaic embryos — those containing a mixture of chromosomally normal and abnormal cells — present a challenging clinical dilemma. Some studies have shown that mosaic embryos can implant and result in healthy births, with the chromosomally abnormal cells disappearing during development. However, they carry higher rates of implantation failure and miscarriage than fully euploid embryos.

Current guidance from reproductive genetics societies is that mosaic embryos can be transferred if no euploid embryos are available, after thorough counselling of the couple about the risks and uncertainties involved. Each mosaic embryo classification (degree of mosaicism, which chromosomes are affected) requires individual consideration.

Cost of PGT-A in India

In India, PGT-A is an additional cost on top of the standard IVF package. Typical costs in 2026:

• Embryo biopsy: ₹10,000–₹20,000 (performed at the IVF clinic)
• Genetic analysis per embryo: ₹15,000–₹25,000 per embryo (performed at a specialist genetics lab)
• Total for 3–5 embryos tested: ₹30,000–₹50,000 additional

When evaluating cost, it is worth considering that PGT-A can reduce the number of failed transfers (each of which has its own financial and emotional cost) in high-risk groups. For a 40-year-old doing multiple IVF cycles, the cost of repeated failed untested transfers can exceed the cost of PGT-A over the same period.

PGT-A and Mosaic Embryo Transfer — What to Ask Your Doctor

Before deciding on PGT-A, ask your fertility specialist:

1. What is my aneuploidy risk based on my age and previous cycle data?
2. Is PGT-A recommended based on my specific clinical history, or is it being offered routinely to all patients?
3. What will you do if I have mosaic embryos — will you transfer them?
4. What happens if all embryos are aneuploid — what are my options?
5. Which genetics laboratory do you use for analysis, and what technology do they use?
6. Is the biopsy included in the package price or charged separately?

Frequently Asked Questions